例子：

#include <stdio.h>

String inputString = “”; a string to hold incoming data boolean stringComplete = false; whether the string is complete

void setup() {

// initialize serial:
Serial.begin(9600);
// reserve 200 bytes for the inputString:
inputString.reserve(200);

}

void loop() {

//serialEvent(); //call the function
// print the string when a newline arrives:
int num = 0;
if (stringComplete) {
  Serial.println(inputString);
  sscanf(inputString.c_str(), "R%d",&num);
  Serial.println(num);
  // clear the string:
  inputString = "";
  stringComplete = false;
}

}

/*

SerialEvent occurs whenever a new data comes in the

hardware serial RX. This routine is run between each time loop() runs, so using delay inside loop can delay response. Multiple bytes of data may be available. */ void serialEvent() {

while (Serial.available()) {
  // get the new byte:
  char inChar = (char)Serial.read();
  // add it to the inputString:
  inputString += inChar;
  // if the incoming character is a newline, set a flag
  // so the main loop can do something about it:
  if (inChar == '\n') {
    stringComplete = true;
  }
}

}